Field of the Invention
The present disclosure relates to a filtering module and a power supply device. More particularly, the present disclosure relates to an electromagnetic interference (EMI) filter and a power supply device with the electromagnetic interference filter.
Description of Related Art
Reference is made to FIG. 1, which is a schematic view of a conventional inductor. The inductor 3 includes a magnetic core 30, a primary winding 32, and a secondary winding 34. The magnetic core 30 has a toroidal shape, and an outer surface and an inner surface of the magnetic core 30 are smooth surface. The primary winding 32 and the secondary winding 34 are wound on the magnetic core 30. When a current is conducted to the primary winding 32, an induced current is generated in the secondary winding 34.
The inductor 3, however, has a constant inductance; i.e. no matter the inductor 3 is operated under heavy current or light current condition, the inductor 3 has the same inductance. As such, the gain and corner frequency (and/or the center frequency) of the electromagnetic inference filter cannot be adjusted.